The proposed study addresses itself to direct measurement of the contact stress distributions characteristic of the normal hip and knee. Since this important problem has not lent itself to conventional measurement techniques, only indirect estimates and simplified models are currently available. Pilot work in our laboratory has shown that highly compliant miniature transducers incorporating piezoresistive elastomers are well suited for articular contact stress measurements. The signals from arrays of 20 such transducers, mounted in the articular cartilage of fresh autopsy specimens (40 hips and 40 knees), will be processed computationally and assembled into contour mappings of the contact stress distributions. Cyclic (l Hertz) loading of the joints to physiological levels will be performed in an Instron unit. The immediate results promise to be of significance in the areas of cartilage pathomechanics, prosthetic joint resurfacing, and stress analysis; the transducers themselves are potentially applicable to a wide range of current biomechanical measurement problems.